JAMB - Physics (2019 - No. 98)
The height at which the atmosphere ceases to exist is about 80km. If the atmospheric pressure on the ground level is 760mmHg, the pressure at a height of 20km above the ground level is
(ρm = 13.6g/cm\(^3\) ρ = 0.00013g/cm\(^3\) )
(ρm = 13.6g/cm\(^3\) ρ = 0.00013g/cm\(^3\) )
380mmHg
570mmHg
190mmHg
480mmHg
Explanation
ρ\(_m\)h\(_m\) = ρ\(_a\)h\(_a\)
13.6(760 - p) × 10\(^{-3}\) = 13 × 10\(^{-5}\)(20 × 10\(^3\))
| 760 | - | p | = | 13 × 10\(^{-5}\) × 20 × 10\(^{3}\)
13.6 × 10\(^{-3}\) |
= | 19.12 | × | 10\(^{1}\) |
760 - p = 191.2
p = 760 - 191.2 ≈ 570mmHg
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